linux-kernel - Re: [PATCH 3/4] brd: Fix all partitions BUGs

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Date:	Thu, 07 Aug 2014 12:53:50 -0600
From:	Ross Zwisler <ross.zwisler@...ux.intel.com>
To:	Boaz Harrosh <boaz@...xistor.com>
Cc:	Jens Axboe <axboe@...nel.dk>,
	Matthew Wilcox <willy@...ux.intel.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH 3/4] brd: Fix all partitions BUGs

On Wed, 2014-08-06 at 14:33 +0300, Boaz Harrosh wrote:
> This patch fixes up brd's partitions scheme, now enjoying all worlds.
> 
> The MAIN fix here is that currently if one fdisks some partitions,
> a BAD bug will make all partitions point to the same start-end sector
> ie: 0 - brd_size And an mkfs of any partition would trash the partition
> table and the other partition.
> 
> Another fix is that "mount -U uuid" did not work, because of the
> GENHD_FL_SUPPRESS_PARTITION_INFO flag.
> 
> So NOW the logic goes like this:
> * max_part - Just says how many minors to reserve between devices
>   But in any way, there can be as many partition as requested.
>   If minors between devices ends, then dynamic 259-major ids will
>   be allocated on the fly.
>   The default is now max_part=1, which means all partitions devt
>   will be from the dynamic major-range.
>   (If persistent partition minors is needed use max_part=)
> 
> * Creation of new devices on the fly still/always work:
>   mknod /path/devnod b 1 X
>   fdisk -l /path/devnod
>   Will create a new device if (X / max_part) was not already
>   created before. (Just as before)
> 
>   partitions on the dynamically created device will work as well
>   Same logic applies with minors as with the pre-created ones.
> 
> TODO: dynamic grow of device size, maybe through sysfs. So each
>       device can have it's own size.
> 
> Signed-off-by: Boaz Harrosh <boaz@...xistor.com>


Tested-by: Ross Zwisler <ross.zwisler@...ux.intel.com>


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